Directional control valve



Nov. 5, 1968 G. J. MARTIN 3,409,041

DIRECTIONAL CONTROL VALVE Filed Feb. 18, 1966 2 Sheets-Sheet 1 E j: T A N K /7 E'. ...Z INVENTOR J GEORGE .1. MART/N Ma,%y d flan/1W ATTORNEYS Nov. 5, 1968 G. J. MARTIN 3,409,041

DIRECTIONAL CONTROL VALVE Filed Feb. 18, 1966 2 Sheets-Sheet 2 INVENTOR GEORGE J. MART/IV ATTORNEYS United States Patent 3,409,041 DIRECTIONAL CONTROL VALVE George J. Martin, Lyndhurst, Ohio, assignor to Parker- Hannifin Corporation, Cleveland, Ohio, a corporation of Ohio Filed Feb. 18, 1966, Ser. No. 528,581 4 Claims. (Cl. 137-596.2)

ABSTRACT OF THE DISCLOSURE A spool valve assembly including upstream and downstream bores for receipt of valve spools therein movable to operating positions blocking the flow through a bypass passage and directing the flow to associated motors. All of the return flow from the motor associated with the upstream valve spool is directed to the bypass passage between the bores for actuation of the motor associated with the downstream valve spool, and there is a check valve in the passage of the upstream valve spool which permits flow of return fluid only in the direction from the associated motor to the bypass passage. Thus, the passage in the upstream valve spool may extend between the upstream portion of the bypass passage and the return passage when the upstream spool valve is in an operating position without permitting flow in that direction because of the check valve therein.

The present invention relates generally as indicated to a directional control valve, and more particularly, to a spool type directional control valve.

It is known in the art to provide directional control valves having unitary cast housings in which a plurality of spools are operable to control a corresponding number of fluid motors, and said housings usually having cored passages that intersect the bores in which said spools are reciprocated. In the case of multiple spool-type directional control valves it is the general practice to provide a cast housing having cored passages which intersect the bores in which the respective spools are reciprocated to control the operation of the respective fluid motors that are connected to the cored motor passages. Quite often, such cored passages comprise a central bypass passage leading from a pressure inlet passage to a return passage and intersecting all of the spool bores; pairs of pressure feed passages intersecting the respetcive spool bores and straddling said bypass passage; pairs of motor passages intersecting the respective spool bores and straddling the respective pairs of pressure feed passages; and a pair of return passages intersecting all of the spool bores and straddling the respective motor passage and leading to the same return passage to which the bypass passage leads.

A multiple spool valve housing of the type aforesaid is disclosed in the patent to Schmiel 3,216,443, granted Nov. 9, 1965 in which the same basic casting and coring is employed either for a parallel circuit (any one or more, or all spools may be operated to control the respective fluid motors), or for a series-parallel circuit (only one spool at a time may be operated to control its respective fluid motor). The aforesaid Schmiel Patent 3,216,443 does not, however, contemplate the use of the same basic housing casting for a series circuit (any one spool may be operated to control its respective fluid motor and if two spools are operated simultaneously, the returning fluid from the upstream motor is utilized for the operation of the downstream motor).

Hitherto, a multiple spool valve assembly for a series circuit has required the employment of a housing casting with passage coring different from that used, for example, in the housing of Schimel Patent 3,216,443 for both parallel and series-parallel circuits. If the series passages are to be in the valve housing, the return passages for the upstream spool must be isolated from the return passages for the downstream spool thus requiring a coring change from a parallel or series-parallel housing wherein the return passages intersect all spool bores. (See, for example, Olsavsky Patent 3,195,571, granted July 20, 1965.) On the other @hand, if the series passages are to be inside the upstream spool, the lands in the upstream spool bore between the adjacent motor and return passages must be of greater width to preclude fluid communication between the inlet passage and a return passage through a series passage in the spool not then in use while another series passage in the spool is returning fluid from a motor passage to a pressure feed passage of the downstream spool. This again requires a coring change from the parallel or series-parallel housing.

In view of the foregoing, it is a principal object of this invention to provide a multiple spool directional control valve for series circiut operation which utilizes the same housing casting as is employed for parallel or seriesparallel circuit operation.

It is another object of this invention to provide a multiple spool directional control valve which is characterized in that all that is required to convert a series-parallel valve to a series valve is to use a hollow upstream spool which has a check valve therein, thereby avoiding any change in passage coring in the housing casting.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

FIG. 1 is a schematic piping diagram showing a twospool series type directional control valve which provides for independent operation of either of the two fluid motors and for series operation of said motors when both spools are in an operating position, the discharge from the upstream fluid motor being conducted to the pressure feed of the downstream spool; and

FIG. 2 is a cross-section view of the valve taken in a plane passing through the axes of the spools.

Referring now more particularly to the drawing, there is provided herein a two-spool directional control valve 1 having its pressure inlet port 2 connected by way of conduit 3 to the discharge port of the pump 4 and having its return port 5 connected by way of conduit 6 with the tank 7. The valve 1 as aforesaid, has two spools 8 and 9 movable therein to control operation of the respective fluid motors 10 and 11 connected by the respective conduits 12; 12 and 14; 14 to the respective pairs of motor ports 15; 15 and 16; 16 of the directional cont-r01 valve 1. As will be seen from later detailed reference to FIG. 2, when the upstream spool 8 is shifted downwardly (or upwardly) from the neutral position shown in FIG. 1, fluid under pressure will be conducted to the bottom (or top) motor port 15 to actuate the piston of the fluid motor 10 toward the right (or left) and the fluid displaced by said fluid motor 10 will be conducted to the return port 5 via the top (or bottom) motor port 15. When the downstream spool 9 is actuated, as described above, in connection with upstream spool 8, the piston of the downstream fluid motor 11 will be operated in corresponding directions. Thus with spool 8 in the upstream location the (a) upstream and downstream bores for reciprocation of valve spools therein,

(b) a bypass passage intersecting both bores and adapted for connection at its respective upstream and downstream ends to a fluid pressure source and to a fluid reservoir,

(c) pressure feed passages intersecting the respective bores and communicating respectively with portions of said bypass passage upstream of the respective bores,

(d) motor passages intersecting the respective bores and adapted for connection with corresponding fluid motors, and

(e) a return passage intersecting both bores and communicating with the downstream end of said bypass passage;

upstream and downstream valve spools movable in the respective bores from a neutral position whereat said bypass passage is open for flow of fluid from the upstream end to the downstream end thereof to operating positions whereat said bypass passage is blocked thereby and, in the case of said upstream valve spool, the respective motor passage is selectively communicated with the respective pressure feed passage or with a portion of said bypass passage between said bores through a passage in said upstream valve spool, and in the case of said downstream valve spool, selectively communicated with the respective pressure feed passage or with said return passage; said passage in said upstream valve spool communicating said return passage with the upstream portion of said bypass passage when said upstream valve spool is in an operating position communicating the respective pressure feed and motor passages; and a check valve means in the aforesaid passage of said upstream valve spool preventing fluid flow through said passage from the upstream portion of said bypass passage to said return passage.

2. A spool valve assembly comprising a housing having (a) upstream and downstream bores for reciprocation of valve spools therein,

(b) a central bypass passage intersecting both bores and adapted for connection at its respective upstream and downstream ends to a fluid pressure source and to a fluid reservoir,

(c) pairs of pressure feed passages straddling said bypass passage and intersecting the respective bores and communicating respectively with portions of said bypass passage upstream of the respective bores,

(d) pairs of motor passages straddling the respective pairs of pressure feed passages and intersecting the respective bores and adapted for connection with corresponding fluid motors, and

(e) a pair of return passages straddling said pairs of motor passages and intersecting both bores and communicating with the downstream end of said bypass passage; upstream and downstream valve spools movable in the respective bores from a neutral position whereat said bypass passage is open for flow of fluid from the upstream end to the downstream end thereof to either of two operating positions whereat said bypass passage is blocked thereby and in the case of said upstream valve spool, the respective motor passages are selectively communicated with the adjacent pressure feed passage or with a portion of said bypass passage between said bores through passages in said upstream valve spool, and in the case of said downstream valve spool, the respective motor passages are selectively communicated with the adjacent pressure feed passage or with the adjacent return passage; said passages in said upstream valve spool communicating one or the other of said return passages with the upstream portion of said bypass passage when said upstream valve spool is in an operating position communicating one or the other of said pressure feed passages with the associated motor passage; and check valve means in the afores-aid passages of said upstream valve spool preventing fluid flow therethrough from the upstream portion of said bypass passage to said return passages.

3. In a multi-spool valve assembly wherein valve spools are selectively movable in bores of a housing from neutral position to operating position to control operation of corresponding fluid motors operatively connected to said housing while at the same time closing a bypass passage through said housing when moved to an operating position, the improvement which comprises providing in one valve spool which is upstream with respect to another valve spool, a passage means through which all of the returning fluid from the associated motor flows to the bypass passage downstream of the bore in which said one valve spool is movable for return to a reservoir when said another valve spool is in neutral position or for actuation of the motor associated with said another valve spool when the latter is in operating position closing said bypass passage.

4. The multi-spool valve assembly of claim 3 wherein a check valve means in the passage of said one valve spool permits the flow of return fluid only in the direction from the associated motor to the bypass passage downstream of the bore in which said one valve spool is movable.

References Cited UNITED STATES PATENTS 3,262,467 7/1966 Stacey 137-5962 3,216,443 11/1965 Schmiel 137596.13 XR 2,949,097 8/1960 Vander Kaay 137-625.68

HENRY T. KLINKSIEK, Primary Examiner. 

